My basement walls were painted before I purchased my home. In some areas the paint is peeling up and there is efflorescence behind the bubbles. We had problems with water when we first moved in, but since we replaced the sump pump we haven't had any new flooding. I want to remove the paint and clean the efflorescence before coating the cinder blocks with a masonry waterproofer. Even though I think the moisture problems are solved, this would give me added piece of mind. What is the best way to prepare the walls? Thank you.

Hi you, There's no easy or fast way to do it.some brands of moisture blocking products can't be used over paint. Is this room in a place that can be pressure washed? Maybe a heat gun will take off some paint on the flat surface but not in the pores. Maybe try the heat gun and some kind of wire brush that will clean out the pores. Paint strippers will burn your skin and eyes and they are explosive, could be ignighted by a gas furnance or hot water tank. Look at Homer Formbies line of products. Some of them are not flamable. Call a full fledged paint store, not wall Mart, for other info. I'm glad It's you and not me on this job. Barb

I'm glad you responded because I was hoping for some sort of solvent/stripper based method to solve my problems but definitely do not want to blow up the basement. The Methylpyrrolidone based stripper I was looking into does appear to have flammable vapors that I want to avoid now that you've pointed it out. Unfortunately power-washing and excessive wire brushing are probably both off the table.

There are non-toxic techniques to paint removal, however nothing is a fast and easy way, other than powerwashing, but that's not recommended in a basement.
Also, interior basement walls really shouldn't be sealed. They should be sealed on the exterior. The interior should be opened to the air so it can dry out in the event moisture does get trapped in the pores. A breathable paint would be recommended for basement walls if you wanted them painted. If its moisture problems you are trying to solve, it should be fixed from the exterior.

Cinderblock is hollow and very porous. If water is not redirected away from the house, the cinderblock can fill up with water. As the cinderblock fills up with water it can push calcium or salt deposits to the surface. Most cindeblock basements have efflorescence forming toward the bottom of the wall, but in more sever cases efflorescence can form all over the wall.

There are several ways to remove paint and efflorescence. First, remove as much of the paint from the wall as possible. Typically this is done with a wire brush or sandblasting machine. Next, you want to use an acid based cleaner (acid etch the surface). Once the concrete has been neutralized you want to seal the cinderblock to prevent further efflorescence from forming.

If you choose to paint your cinderblock again, you can do so with any concrete paint after the block has been sealed with a waterproofing sealer, like the Armor S2000.

I have old chipping paint and what I think may be efflorescence in my basement. I want to clean it up and paint the cinderblock wall white in addition to sheetrocking an inside wall and the ceiling to make a nice, clean storage room.

However, I am a little confused because I hear some people say not to seal the cinderblock from the inside because then the concrete cannot breath. But now you say that I should seal it after having stripped it using Armor S2000. Also can you recommend a concrete paint? Also when I talked to the paint store they said I should just use latex paint as long as I prime the surface.

I really apprecieate any additional information you can provid! Thank you